The invention relates to harmonizing, relative to the terrestrial frame of reference, a frame of reference of an angular positioner that is adapted to receive a moving body or a flying vehicle for which it is desired, for example, to test its performance (e.g. a missile, an airplane, a rocket, etc.).
Harmonizing the frame of reference of the angular positioner relative to the terrestrial frame of reference is used herein to mean orienting axes of the angular positioner relative to the axes of the terrestrial frame of reference, i.e. orienting an axis of the frame of reference of the angular positioner in the geographical north position and positioning the other two axes of the frame of reference of the angular positioner relative to the vertical at the location of the positioner (i.e. one of them oriented along the local vertical and the other one perpendicular to the vertical).
By way of example, the angular positioner may be an angular movement simulator, a test bench, or a micrometric table. It may be used in particular in the context of hybrid simulation, as described in document FR 2 927 418.
The invention thus applies in preferred but non-limiting manner to the field of aviation.
In known manner, a moving body suitable for mounting on such an angular positioner is conventionally provided with an inertial measurement device having gyros (rate gyros and/or free gyros) and/or accelerometers, such as an inertial unit. The inertial measurements delivered by the measurement device relate in particular to the angular speed and/or the acceleration of the moving body to which it is fitted.
Harmonizing the frame of reference of the angular positioner relative to a given frame of reference, typically relative to the terrestrial frame of reference, makes it easier to make use of the inertial measurements delivered by the measurement device during hybrid simulation.
Harmonization also makes it possible to avoid falsifying navigation of the moving body that is being carried by the angular positioner for the purpose of testing the performance of that moving body.
In addition, harmonizing the frames of reference with each other ensures that the test carried out on the moving body (or on its equipment, e.g. the inertial unit of the moving body) are repeatable and accurate, thereby guaranteeing that the results of the hybrid simulation are reliable.
In order to perform such harmonization, it is known to have recourse to expensive pieces of equipment that are not readily available, such as a north seeker, a theodolite, and/or high precision electronic level-measuring instruments, as described in particular in document FR 2 927 418. Nevertheless, using such equipment makes it necessary to rely on qualified personnel.
When a repair is carried out on the angular positioner as a result of a breakdown, it often happens that the angular positioner is no longer properly referenced relative to the terrestrial frame of reference, i.e. the frame of reference of the angular positioner is no longer harmonized relative to the terrestrial frame of reference. It is then difficult to make available quickly the equipment and the personnel needed for harmonizing the frames of reference relative to each other once more, and that can be harmful to progress in the tests being carried out on the moving body.
There therefore exists a need to have a method of harmonizing the frame of reference of the angular positioner relative to the terrestrial frame of reference that does not suffer from such drawbacks, and in particular that enables the frames of reference to be harmonized relative to each other in a manner that is simple and reliable and in a length of time that is relatively short.